I think perhaps a BF2 would need a "re-definition" of classes. Maybe exaggerate their strengths a little. Like CIS are strongly anti-vehicle, Republic anti-personal, Imperial, overall Strong, Rebels, fast and flexible. (With obvious exceptions, which are the special units).

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I've always thought a Gian Speeder driven Halo 2 style with people shooting from their seats to be too good! *hint, hint*